Intradiol ring fission

In strain RH025, a hydrolytic mechanism brought about the loss of fluoride to produce 4-hydroxybenzoate, which was further hydroxylated to 3,4-dihydroxybenzoate before intradiol ring fission (Figure 9.33a). 

Trihydroxybenzene is an intermediate in the degradation by Phanerochaete chrysosporium of vanillate, 2,4-dichlorophenol, 2,4-dinitrophenol, and 2,7-dichlorodibenzo[l,4]dioxin (Chapter 6, Sections 6.5.2,6.8.2 and 6.3.2, respectively), and its degradation is mediated by a dioxygenase that carries out intradiol ring fission (Rieble et al. 1994). 

Sulphite may not necessarily be elimination before ring fission, and the degradation of sulfanilate by a mixed culture of Hydrogenophaga palleroni and Agrobacterium radiobacter proceeds via catechol-4-sul-fonate and intradiol ring fission sulfite is then elimination from the muconolactone (Hammer et al. 1996). 

The second large group of ring-fission dioxygenases are used for the degradation of ortho-dihy-droxybenzoates including, 2,3-, 3,4-, and 4,5-dihydroxybenzoate. As for simple catechols, hssion may be either intradiol or extradiol, and the choice between them depends on the organism ... 

After formation of the 1,2-dihydroxy compounds, ring fission is mediated by 1 2 (intradiol fission) or 2 3 (extradiol and distal fission) dioxygenases. There are, however, important variations in the pathways used by various groups of microorganisms ... 

Ring fission. Ring fission of substituted catechols may take place by three pathways intradiol (ortho), extradiol (meta), or distal (1 6) fission. Although extradiol fission is generally preferred for substituted catechols, the product from extradiol fission of... 

The degradation of 3-chloro-4-methylaniline by Pseudomonas cepacia strain CMAl involved ring fission of 3-chloro-4-methylcatechol by an intradiol enzyme (Stockinger et al. 1992). 

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